Sodium lamp



June 7,1938. D s 'GUSTlN 2,119,675

soDIUM LAMP Filed Jan. 3l, 1956 l mw:

INVENTOR. ..5'. GMS/WV ATT EY.,

Patented June "7, 1938 UNITED STATES -PATENT formes SODIUM LAMP v DanielS. Gustin, Bloomileld, N. J., assignor, by

mellle nts, to Westinghouse Electric and Manufacturing Company, EastPittsburgh,

Pa., a corporation of Pennsylvania Application January 3l, 1936, SerialNo. 61,836

' s claims.

This invention relates to a discharge de vice of the type employingelectrodes which operate to provided a heater invthe form of a coil ofany suitable refractory wire such as, for example, nichrome and theelectrodes are so formed as to serve as closing ends for the envelope inwhich Furthermore, the

the discharge takes place. heater elements-are replaceable so that inthe event that a heater burns out it" may be conveniently replaced atlow cost.

It is an object of the present invention to provide a discharge devicewith electrodes so a'rranged as to be heated by removable heater ei- 0ments.

. Another object or the invention is to provide a discharge device withelectrodes serving as end closures iol-,a bulb.

Another object of the invention is to provide 5 a discharge device withtubular operating electrodes and replaceable heater units for saidelectrodes. f Other objects and advantages oi the" invention will bemore clearly understood by reference to the following descriptiontogether with the accompanying drawing in which Fig. l is 'a sideelevational view of a lamphaving electrodes constructed in accordancewith the present invention and showing a diagram of the 5 source ofelectrical energy to operate the device;

Fig. 2 is an enlarged sectional view showing one end of abulb and anelectrode positioned therein; l

Fig. 3 is an enlarged end view of the lamp; an

Fig. 4 is a side viewA o! one of the heater units removed from the lamp.

A selected embodiment ofthe invention may, as shown, comprise a tubularbulb il consisting' of a cylindrical glass tube Il having its ends l,closed by a reentrant tube i2 provided with a together with a smallamount of f megas', such the tube sealed by pinching oi.

flange ls, the edge u of which is desirebly aimed with and sealed to theedge I5 ofthe tube. 'I'he reentrant tube i2 constitutes an electrode;the outer .surface of which is provided with a coating I6 of electronemission material. Each end of the tubel Il is provided with anelectrode of the construction just described. These electrodes may bemade of sheet'metai, such as molybde num, which will wet with the glassIct has been found in practice that molybdenum isa good material andseais made with glass known under the trade designation o1' G-705'A. J.Code No. 705,

(see page '135, v01. 22o, Journei of. Framura Insutute and pages 394-6,403 and 5, vol. 5 of Physics) have been satisfactory. The electrodes maybe spun or drawn from the sheet material, and a tubular extension il maybe provided through which the bulb maybe exhausted .and

Each electrode is provided with a replaceable heater unit i8 consistingof a plug I9 in the form of a metal shell having an axial contact 2iinsulated from the sheetlby a glass' web 22. Extending from'the innersurface of the plug, is a stem of insulative material' through whichconductors 23 and 2l extend. One end of conductor 23 connects with thecontact 2| and one end of conductor 2l connects with the metallic shellIt. The other ends of the conductors project from the stem and connectwith the terminals of a heater element 25 in the form of a refractorycoil having the required properties to serve as a heater. e

Around the stem I8 is a casing 26 which may Q provided with threads toengage threads formed y in the'eiectrode i2 sothat when thefheater unitis inserted -it may be scewedinto rm contact with the electrode wall.Each endof the tube III may be provided with a cap `2l heldin place by asuitin place the cap is provided with locking plates 32 and 3l providedwith teeth 24 and 35 to 'enf-- cure the heater unit againstremoval.

The'present device may be supplied with electrical energy by anysuitable means and, as shown.'

a transformer 4I connected to a supply source (not shown) has asecondary winding tapped to provide .a source of electrical energy foreach heater element. Conductors 4i and I2 provide electrical energy forone heater unit and conductors' and 44 provide electrical energy for theother heater unit.

The heaters elevate the temperature of the coatings on the electrodesrenderingqthem electron emissive and causing an ionization of the gas.'Ajpotential is applied to the electrodes I2 and I2 by reason ofthewinding I! of the transformer 4 0, and when the ionized gas becomessuiiiciently conductive, current ows between the electrodes to support adischarge.

The present construction provides a discharge tube which will have along life since in devices or this character the-heater element has -arelatively 'short life whereas theotherlparts have a long operatinglife. With the present replaceable heater unit the more expensive partof the device consisting of the bulb and electrodes may be operated overlong periods of time and when ynecessary new heater units may besupplied.

Although 'a preferred embodiment of the invention' is shown anddescribed herein, it is to be understood that modifications may be madetherein without departing from thev spirit and scope of the invention asset forth in the appended claims.

I claim:

l. -A discharge device comprising a bulb open at one end, an electrodeextending into said bulb and having one end sealed to the end of thebulb to provide a closure, and a removable heater element threadablyconnected to said electrode, said element comprising af metal shellpartly filled with 'insulative material to leave a cavit and a heating.devicein 'said cavity.

2.l A discharge device comprising a bulb having one end open, a tubularelectrode having one end closed and positioned within said bulb, a

ilange integral with the open end oi said electrode and lsealed to theopen'end of said bulb to provide a closed container,l a heaterelementposi- A tioned within, and threadably connected to said electrode, andmeans to prevent unscrewing of Vsaid element comprising a cap secured tosaid bulb and formed with an aperture through which passes theouter endof said element and plate means adiustably secured to said cap' andformed with teeth engageable with corresponding teeth on said' element.

3. A discharge device comprising a tubular bulb, a metallic closuresealed to one end of said bulb, an electrode integral with said closureand extending into said bulb, and a heater element threaded into saidelectrode, said element comprising a shell partly illled with insulatingmaterial, leaving a cavity, and a refractory illament I mounted in saidcavity and adapted to be energized.

4.,.A4discharge device comprising a tubular bulb, a metallic closurewith an outer ilange portion sealed to one end of said bulb and havingan electrode integral therewith and extending into said bulb, saidelectrode having its inner or active end portion helically threaded, anda heater element for said electrode. said element being removablysecured to said electrode by cooperating helical threads formed thereon.

5. A discharge device comprising a cylindrical bulb of generally uniformdiameter open at one end, a metallic closure member, said closure membercomprising a reentrant tube with a central portion forming an electrodeextending into said bulb, and a ilange portion connected to said centralportion by a ilared intermediate part, said ilange portion beinggenerally cylindrical and oi a diameter corresponding with that of saidbulb, sealed to the end of said bulb wall, and forming an alignedextension`thereon, and a heater element threaded into said electrode,said element comprising a shell partly iilled with insulating materialleaving a cavity, and heating means disposed in said cavity.

' DANIEL S. GUSTIN.

